This topic describes the configuration parameters of a connection pool, including ZDAL parameters, Druid parameters, DBCP parameters, C3P0 parameters, and JDBC parameters.
Data source configuration parameters
Parameter definition |
Description |
ZDAL parameter |
Druid parameter |
DBCP parameter |
C3P0 parameter |
|---|---|---|---|---|---|
| Number of initial connections | The number of connections established during initialization of the connection pool. | prefill=true, initialized to minConn | initialSize(0) | initialSize(0) | initialPoolSize(3) |
| Minimum number of connections | The minimum number of available connections retained for the connection pool. | minConn(0) | minIdle(0) | minIdle(0) | minPoolSize(3) |
| Maximum number of connections | The maximum number of available connections. If the number of connections in the connection pool exceeds this number, an exception is returned, indicating that the connection pool is full. | maxConn(10) | maxActive(8) | maxActive(8) | maxActive(8) |
| Connection idle timeout period | The period of connection idle time that the connection pool waits for before it disconnects the connection. MySQL disconnects a connection that has been idle for 8 hours by default. A connection becomes a dirty one during the active/standby switchover. Without this mechanism, a request may fail. For OceanBase Cloud, the default Server Load Balancer (SLB) timeout period is 15 minutes. You can set it to 12 minutes. | idleTimeoutMinutes(30min) | minEvictableIdleTimeMillis(30min) | minEvictableIdleTimeMillis(30min) This parameter takes effect only when timeBetweenEvictionRunsMillis(-1) is set to a positive value. This parameter specifies the asynchronous check cycle. |
maxIdleTime (0 indicates no timeout.) |
| Timeout period for obtaining a connection from the connection pool | If the value is too large, the application response will be very slow when the connection pool is full. | blockingTimeoutMillis(500ms) | maxWait (-1 indicates no timeout.) | maxWaitMillis (-1 indicates no timeout.) | checkoutTimeout (0 indicates no timeout.) |
| Timeout period before destroying a connection | If a connection is not returned to the connection pool after this period, the connection is directly destroyed. This mechanism prevents connection leakage but restricts the duration in which a connection can be used by a transaction. | None | removeAbandonedTimeoutMillis(300s) | removeAbandonedTimeout(300s) | None |
JDBC configuration parameters
The following JDBC parameters are important and must be configured. You can specify these parameters in the connection properties of the connection pool or in the JDBC URL. The following table describes the parameters.
Parameter |
Description |
|---|---|
| socketTimeout | The network socket timeout period (SO_TIMEOUT), in ms. The value 0 specifies to disable socket timeout. You can also set the system variable max_statement_time to limit the query time. Default value: 0 (in standard configuration). |
| connectTimeout | The connection timeout period, in ms. The value 0 specifies to disable connection timeout. Default value: 30000. |
Suggestions on connection pool settings
You can retain a minimum of two connections for the console and adjust the configuration based on the business concurrency and transaction time.
We recommend that you set the idle connection timeout period to 30 minutes.
By default, MySQL disconnects a connection that has been idle for 8 hours, which cannot be sensed by the client. This results in dirty connections. The connection pool can check whether a connection is alive through mechanisms such as heartbeats or testOnBorrow. When the connection has been idle for this period, the connection is disconnected.